On Feb. 4, 1970, the tanker Arrow struck Cerberus Rock in the entrance to Chedabucto Bay, Nova Scotia in bad weather. Most of the cargo of 16,000 tons of Bunker C oil was lost into the icy waters. The spill was extensively studied and reported upon because more spills in icy waters are expected to occur as more oil is produced from wells in the Artic region.
One report of the spill, delivered at the Fourth Annual Offshore Technology Conference held at Houston, TX on May 1-3, 1972, is Paper Number OTC 1522, The Behavior of Oil Spilled in a Cold Water Environment, by A. Y. McLean of Nova Scotia Technical College. The report concludes that, while spilling oil in ice waters is initially blessed by the capacity of the ice and coldness to confine the spill to a smaller geographical area, the problem of recovery of oil from oil-water-ice slurry is insoluble, the removal of oil trapped in ice is extremely difficult, and the problem of recovering oil from a mixture of oil and ice is virtually insurmountable. The report further concludes one must wait until the seasons progress and the weather warms and the ice melts before oil recovery is feasible. Of course, the thawing permits the spilled oil to spread, and the earlier effect of containment of the spill by ice is lost.
Exploration for energy resources in the Arctic and in other ice covered waters is occuring at an everincreasing rate to alleviate the current shortages of oil and gas. With this increase in activity, there is need for a device which can effectively clean up oil which accidentally (or by nature) comes in contact with ice. Such occurrences could result in a single spill with tons of oil under the ice or mixed with broken ice floes. Such spills could also result from ships moving in the Arctic waters. At best, today, one would have to wait for the ice to melt before beginning clean-up procedures. Such a wait could result in such wide dispersion of the oil that contamination would extend for hundreds of square miles. Under these circumstances, clean-up would be unfeasible; hence, a need exists to recover the oil while ice is present.
The present inventors initially considered the feasibility of scooping up as much of the contaminated ice and spilled oil as possible and using the recovered oil for fuel to melt all of the contaminated ice so the oil could be separated therefrom. However, calculations have shown that for most spills the heat needed to melt all the contaminated ice will exceed that available from burning the recovered oil. The realization led to development of the present invention.
In designing the process and apparatus of the present invention, the inventors drew upon their combined knowledge and upon the following publications.
I. mcLean, A. Y., "The Behavior of Oil Spilled in a Cold Water Environment", Offshore Technology Conference, OTC 1522 (May, 1972). PA0 Ii. waggner, J. P. and Cappel, K., "Concept Development Program for Icebreaking on the Upper Mississippi River", The Franklin Institute Research Laboratories, Pennsylvania, Technical Report F-C 2717, to the Unites States Coast Guard, Contract No. DOT-CG-00397-A (March, 1971). PA0 Iii. bianchi, R. A., Farrel, J. H., and Johanson, E. E., "Demonstration of Fixed and Moving Inclined Plane Oil Skimmers for Collecting Oil Under the Water Surface", Offshore Technology Conference, OTC 1520 (May, 1972). PA0 Iv. bianchi, R. A., Farrell, J. H., and Johanson, E. E., "The Application of Skimmers, Piston Films, and Sorbents for Open Water Spills", Offshore Technology Conference, OTC 1746 (April, 1973). PA0 V. gollan, A. and Fruman, D. H., "A Filter Coalescer Device for Oil-Water Separation", Offshore Technology Conference, OTC 2127 (May, 1974). PA0 Vi. glaser, J. L., Vance, G. P., "A Study of the Behavior of Oil Spills in the Arctic". Prepared for U.S. Coast Guard Headquarters, Washinton, D. C., Project Number 714108/A/001,002. (Feb. 1971) PA0 Vii. hoult, David P, "The Aging of Oil Spilled in the Arctic", Massachusetts Institute of Technology. (August 1971) PA0 Viii. keevil, Benjamin E, and Ramseier, Rene O., "Oil Pollution in Ice Covered Rivers", Internal Report 22 to Glaciology Division, Water Resources Branch, Department of the Environment, Canada. (May 1974) PA0 Ix. mcMinn, T. J., "Crude Oil Behavior on Arctic Winter Ice". Environmental and Transportation Technology Division, Office of Research and Development for U.S. Coast Guard Project 734108. (Sept. 1972) PA0 X. ramseier, Rene O., "Possible Fate of Oil in the Arctic Basin". First World Congress on Water Resources. (Sept. 1973) PA0 Xi. wolfe, L. S., Hoult, D. P., "Effects of Oil Under Sea Ice", Massachusetts Institute of Technology, for the United States Coast Guard, U.S. Dept. of Transporttion, under Contract Number DOT-CG-12438-A. (August 1972)
In addition, the inventors are aware of some development work done by Chrysler Corporation and others in the early 1960's on the use of Archimedian screw propulsion systems for amphibian vehicles and the like.